Having three primary germ layers, such as ectoderm, mesoderm and endoderm.
All higher and intermediate animals (i.e. from flat worms to humans develop from a triploblastic embryo, in contrast to other organisms (e.g. cnidaria) that develop from a diploblastic embryo.
Word origin: Greek tripló(os), threefold + blastikós, budding.
Related forms: triploblasty.
Compare: monoblastic, diploblastic.
See also: blastula, germ layer.